Apo-Levothyroxine™

Uses of Apo-Levothyroxine™

Levothyroxine is used in adults and children to treat hypothyroidism (underactive thyroid – a condition where the thyroid gland does not produce enough thyroid hormone).

Levothyroxine is also used in adults along with surgery and radioactive iodine therapy to treat a certain type of thyroid cancer.

Levothyroxine injection is used in adults to treat myxedema coma.

Levothyroxine belongs to a class of medications called hormones. It works by replacing thyroid hormone that is normally produced by the body.

Precautions and Warnings

You may not be able to use levothyroxine if you have certain medical conditions. Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder or any heart problems such as a recent heart attack.

Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of this medicine, especially if you are taking any other weight-loss medications or appetite suppressants.

Taking more than your recommended dose will not make this medicine more effective, and may cause serious side effects.

You should not use levothyroxine if you are allergic to glycerin or edetate disodium, or if you have an untreated or uncontrolled adrenal gland disorder.

To make sure this medicine is safe for you, tell your doctor if you have ever had:

• a thyroid nodule;
• thyroiditis (inflammation of thyroid gland);
• heart problems such as a heart attack, stroke;
• a blood clot or a blood clotting disorder;
• diabetes (your diabetes medicine may need to be adjusted);
• anemia (low red blood cells);
• weak bones (osteoporosis), or low bone mineral density;
• problems with your pituitary or adrenal gland;
• an allergy to any food or drugs;
• recently received radiation therapy with iodine (such as I-131); or
• kidney disease.

Tell your doctor if you are pregnant or plan to become pregnant. Having hypothyroidism during pregnancy may increase the risk of premature birth or other complications. The benefit of treating hypothyroidism may outweigh any risks to the baby. Your dose needs may be different during pregnancy.

Tell your doctor if you are breastfeeding. Your dose needs may be different while you are nursing.

You may be more likely to have a broken bone while using levothyroxine. Talk with your doctor about ways to keep your bones healthy.

Dosage

For Hypothyroidism (underactive thyroid):

• Adults (Initial dose): Typically 25 to 50 mcg/day – Adjusted every 6–8 weeks based on TSH levels – Full replacement dose: ~1.6 mcg/kg/day (based on body weight)

• Older adults / Heart disease patients: Start lower: 12.5 to 25 mcg/day – Increases more slowly to avoid cardiac stress

For Congenital Hypothyroidism (infants/children)- Dosing is much higher per kg:

• Newborns: 10–15 mcg/kg/day
• 1–5 years: 5–6 mcg/kg/day
• 6–12 years: 4–5 mcg/kg/day
• >12 years: 2–3 mcg/kg/day

Side Effects

Common Side Effects:

• Increased appetite
• Weight loss
• Heat intolerance / sweating
• Nervousness or anxiety
• Tremors
• Headache
• Insomnia (trouble sleeping)
• Diarrhea
• Menstrual irregularities
• Fatigue (paradoxically)

Serious Side Effects:

• Chest pain or palpitations
• Rapid or irregular heartbeat (arrhythmia)
• Shortness of breath
• Seizures
• Severe headache or vision changes
• Swelling in hands, ankles, or feet
• Allergic reactions (rash, itching, swelling, severe dizziness, difficulty breathing)
• Signs of adrenal insufficiency (extreme tiredness, weakness, dizziness)